no probs at all Fraser
Speed and HPI are probably your best bet. HPI is totally about imports and Speed is mostly imports as well as rexys etc...
Zoom is more technical, "build ups" etc (as you would know).
Motor and Wheels are similar to each other...except that Motor is totally performance car orientated, where I don't think Wheels is as much (I think, i don't buy it, except for the issue where this website got mentioned ). They're not import mags though. But they do feature nice photography and car related stories from overseas, so would be worth a try for what you want.
I really can't think of any others??? They really are the only main ones, as far as i can think of atm...